phpnuke dont work

i have no experience with hosting or cpanel whm, i,m hosting only my own website on a server with cpanel-whm and i have now an other server with olso cpanel-whm, and now on the new server my site phpNUKE webportal 7.6 dont work perfect, if i try to download something i get the error message page not found, after this i lost all php based sites and the cpanel is extremely slow or dont open, the i do a /etc/init.d/cpanel restart and reboot the server then all works again and if i open the site again then i have the same problem again, why is this happening and how to solve this problem and i dont have experience, and i have asked my host and this configuration is a litlle to expensif for me.
i want just run one site in phpNuke is there a simpel way to solve this problem.
Thanks in advance